Compact circular polarized antenna with cavity for additional devices

Abstract

According to one embodiment, an antenna comprises a plurality of elongated side radiating elements having longitudinal axes oriented at angles of between about 10° and about 80° from a line perpendicular to an imaginary base plane extending across ends of the side radiating elements, and a cavity positioned between the side radiating elements defined by at least one non-radio frequency-transparent sidewall. In another embodiment, a system comprises a plurality of elongated side radiating elements each lying along a unique side plane and having longitudinal axes oriented at angles of between about 10° and about 80° from a line perpendicular to an imaginary base plane extending across ends of the side radiating elements, and a cavity being positioned between the side radiating elements defined by at least one non-radio frequency-transparent sidewall, wherein the at least one sidewall has sides each lying along a plane about parallel to the unique side plane.

What is claimed is: 
     
       1. An antenna, comprising:
 a plurality of elongated side radiating elements having longitudinal axes oriented at angles of between about 10 and about 80 degrees from a line perpendicular to an imaginary base plane extending across ends of the side radiating elements; 
 a cavity defined by at least one sidewall, the cavity being positioned between the side radiating elements, the sidewall being non-radio frequency-transparent; and 
 a plurality of top radiating elements each electrically coupled to an associated one of the side radiating elements, each of the top radiating elements extending in a direction that is not collinear with the longitudinal axis of the associated side radiating element, wherein the at least one sidewall extends at least to an imaginary plane extending through the top radiating elements. 
 
     
     
       2. The antenna of  claim 1 , wherein the top and associated side radiating element together form a radiating element, wherein a point of coupling of the top and side radiating elements is at a point along the radiating element where a near magnetic field of the radiating element is between about 60% and about 80% below a maximum near magnetic field of the radiating element. 
     
     
       3. The antenna of  claim 1 , wherein the top radiating elements do not extend over the cavity defined by the at least one sidewall. 
     
     
       4. The antenna of  claim 1 , wherein a width of each of the side radiating elements in a direction perpendicular to the longitudinal axis thereof is between about λ/400 and about λ/20, wherein the top radiating elements are elongated, wherein a width of each of the top radiating elements in a direction perpendicular to a longitudinal axis thereof is between about λ/400 and about λ/20, where λ is a free space wavelength of radiation at a middle frequency of an operational frequency band of the antenna. 
     
     
       5. The antenna of  claim 1 , wherein the top and associated side radiating element together form a radiating element, wherein a point of coupling of the top and side radiating elements is at a point along the radiating element where a near magnetic field of the radiating element is between about 40% and about 60% below a maximum near magnetic field of the radiating element. 
     
     
       6. The antenna of  claim 1  wherein a distance between the imaginary base plane and a plane extending through couplings of the side radiating elements and the top radiating elements is between about λ/6 and about λ/32, where λ is a free space wavelength of radiation at a middle frequency of an operational frequency band of the antenna. 
     
     
       7. The antenna of  claim 1 , wherein the top and associated side radiating element together form a radiating element, wherein a point of coupling of the top and side radiating elements is at a point along the radiating element where a near magnetic field of the radiating element is between about 20% and about 40% below a maximum near magnetic field of the radiating element. 
     
     
       8. The antenna of  claim 1 , wherein the at least one sidewall does not extend along a plane parallel to the imaginary base plane. 
     
     
       9. The antenna of  claim 1 , further comprising a ground plane, wherein the at least one sidewall is electrically conductive and is electrically coupled to the ground plane. 
     
     
       10. The antenna of  claim 1 , wherein the at least one sidewall and the cavity are spaced from the side radiating elements. 
     
     
       11. The antenna of  claim 1 , further comprising a second antenna positioned in the cavity. 
     
     
       12. The antenna of  claim 11 , wherein the second antenna is a patch antenna. 
     
     
       13. The antenna of  claim 11 , wherein the second antenna is a loop antenna. 
     
     
       14. The antenna of  claim 1 , wherein the side radiating elements each lie along a unique side plane, wherein the at least one sidewall has sides each lying along a plane about parallel to the unique side plane. 
     
     
       15. The antenna of  claim 1 , wherein the side radiating elements are tilted, relative to the line perpendicular to the imaginary base plane, towards the imaginary base plane in a direction opposite to a rotation of an electrical component of a field radiated by the antenna. 
     
     
       16. The antenna of  claim 1 , wherein a width of each of the side radiating elements in a direction perpendicular to the longitudinal axis thereof is between about λ/400 and about λ/20, where λ is a free space wavelength of radiation at a middle frequency of an operational frequency band of the antenna. 
     
     
       17. A system, comprising:
 a plurality of elongated side radiating elements each lying along a unique side plane and having longitudinal axes oriented at angles of between about 10 and about 80 degrees from a line perpendicular to an imaginary base plane extending across ends of the side radiating elements; 
 a cavity defined by at least one sidewall, the cavity being positioned between the side radiating elements, the sidewall being non-radio frequency-transparent, wherein the at least one sidewall has sides each lying along a plane about parallel to the unique side plane; and 
 a plurality of top radiating elements electrically coupled to the side radiating elements, each of the top radiating elements having a different orientation than the associated side radiating element. 
 
     
     
       18. The system of  claim 17 , wherein the side radiating elements are tilted, relative to the line perpendicular to the imaginary base plane, towards the imaginary base plane in a direction opposite to a rotation of an electrical component of a field radiated by the antenna. 
     
     
       19. The system of  claim 17 , wherein the top and associated side radiating element together form a radiating element, wherein a point of coupling of the top and side radiating elements is at a point along the radiating element where a near magnetic field of the radiating element is between about 60% and about 80% below a maximum near magnetic field of the radiating element. 
     
     
       20. The system of  claim 17 , wherein a width of each of the side radiating elements in a direction perpendicular to the longitudinal axis thereof is between about λ/400 and about λ/20, wherein the top radiating elements are elongated, wherein a width of each of the top radiating elements in a direction perpendicular to a longitudinal axis thereof is between about λ/400 and about λ/20, where λ is a free space wavelength of radiation at a middle frequency of an operational frequency band of the antenna. 
     
     
       21. The system of  claim 17 , wherein the top and associated side radiating element together form a radiating element, wherein a point of coupling of the top and side radiating elements is at a point along the radiating element where a near magnetic field of the radiating element is between about 40% and about 60% below a maximum near magnetic field of the radiating element. 
     
     
       22. The system of  claim 17 , wherein the top and associated side radiating element together form a radiating element, wherein a point of coupling of the top and side radiating elements is at a point along the radiating element where a near magnetic field of the radiating element is between about 20% and about 40% below a maximum near magnetic field of the radiating element. 
     
     
       23. The system of  claim 17 , wherein the at least one sidewall extends at least to an imaginary plane extending through the top radiating elements. 
     
     
       24. The system of  claim 17 , wherein the top radiating elements do not extend over the cavity defined by the at least one sidewall. 
     
     
       25. The system of  claim 17 , wherein the at least one sidewall does not extend along a plane parallel to the imaginary base plane. 
     
     
       26. The system of  claim 17 , further comprising a feeding circuit having a ground plane, wherein the at least one sidewall is electrically conductive and is electrically coupled to the ground plane. 
     
     
       27. The system of  claim 17 , wherein the at least one sidewall and the cavity are spaced from the side radiating elements. 
     
     
       28. The system of  claim 17 , further comprising a second antenna positioned in the cavity. 
     
     
       29. The system of  claim 17 , further comprising an optical device positioned in the cavity. 
     
     
       30. The system of  claim 28 , wherein the second antenna is a patch antenna. 
     
     
       31. The system of  claim 28 , wherein the second antenna is a loop antenna. 
     
     
       32. The system of  claim 29 , wherein the optical device is a laser barcode scanner. 
     
     
       33. The system of  claim 29 , wherein the optical device is an imaging device. 
     
     
       34. The system of  claim 17 , further comprising a light source positioned in the cavity. 
     
     
       35. The system of  claim 17 , further comprising an identification device positioned in the cavity.